1. Field of the Invention
The invention in general relates to diagnostic apparatus having on-line sensor inputs, and particularly to apparatus which dynamically takes into account failing sensors.
2. Description of the Prior Art
Complex industrial or other operating systems generally having a plurality of sensors for monitoring various parameters during operation, not only for control purposes but for purposes of monitoring the system to detect actual or impending malfunctions.
Some systems may utilize dozens, if not hundreds, of sensors in the diagnostic process and very often the sensors may fail, degrade or provide spurious readings not related to the actual parameter being measured.
Use of erroneous sensor data in the diagnostic process can lead to erroneous conclusions about possible malfunctions. In one respect, a malfunction may be indicated where, in fact, no malfunction exists and conversely a malfunction may be occurring or may occur without its detection and without proper notification to the system operator. Such event can represent a tremendous economic loss as well as a potentially dangerous situation.
Diagnostic apparatus has been proposed which utilizes a rule-based approach for representing diagnostic rules whereby belief leading to a consequent malfunction is propagated, based upon the sensor readings.
The present invention, inter alia, recognizes malfunctioning sensors and functions to dynamically alter the propagation of belief leading to a component malfunction diagnosis by the apparatus thereby reducing the importance of a malfunctioning sensor in the diagnostic process.